Because holographic images are not readily copied by commercial photocopiers, they are frequently integrated into such sensitive items as stock certificates, travelers checks, identification cards, and credit cards for enhanced security. The cost, expense, and potential for security breaches associated with holographic image processes have, however, inhibited the use of holographic images in a number of applications, including game cards.
Conventional holographic images are produced by a stamping process in which a shim, having the mirror image of a three dimensional holographic image formed thereon, is impressed into a reflective surface. The stamped impression causes light to reflect in varying directions from the reflective surface in the form of the holographic image. In one method the shim is impressed into a metallic foil adhered to a substrate. This method is often cost-prohibitive, however, because the step of adhering the metallic foil to a substrate cannot readily be integrated into conventional printing operations. Boswell, U.S. Pat. No. 5,464,690 (incorporated by reference herein), discloses a holographic imaging process in which a shim is impressed into a reflective surface formed by vapor deposition of metallic particles onto a substrate. Boswell's process also may be cost-prohibitive in some circumstances because of the complexity and expense of the vapor deposition process.
In the foregoing holographic imaging processes, a glossy transparent coating may be applied over the holographic image in order to enhance its iridescence or gloss. In another holographic imaging process a glossy transparent coating is applied over a reflective surface before a holographic image is impressed onto the item. The glossy transparent coating is itself impressed by the shim and, depending upon the depth of the impression and the thickness of the transparent coating, the reflective surface may or may not be impressed in the process. The impression of the transparent coating causes light that is reflected from the reflective surface, and which passes through the transparent coating, to refract and thereby create a holographic image.
Because of the complexity and expense of equipment required to manufacture items incorporating holographic images, holographic imaging traditionally has been performed at separate specialty manufacturing sites. The holographic images often are formed on labels that are transported to a separate manufacturing facility to be applied to sensitive items. Because the holographic imaging is performed at a separate site, however, there is a greater potential for illicit application of holographic labels to counterfeit goods, by theft of the holographic labels, than if the holographic imaging were performed on-site. To overcome this problem Boswell, supra, has developed a label that is manufactured at a separate site, but which is applied to the sensitive item and stamped by a shim at the same site that the sensitive items are manufactured. Boswell's process still requires, however, that labels be manufactured at and transported from a separate site, and that a separate label application step be included in the manufacturing process.